This nonprovisional application claims priority under 35 U.S.C. xc2xa7 119(a) on Patent Application No. 2000-260504 filed in Japan on Aug. 30, 2000, which is herein incorporated by reference.
1. Field of the Invention
The present invention relates to a mobile navigation system for displaying map information and the present position information.
2. Description of the Background Art
As a mobile navigation apparatus for displaying a map information and the present position information, the apparatus disclosed in Japanese Published Unexamined Patent Application No. 83684/1995 is well known. This apparatus extracts the map information including the scheduled region for movement before starting the movement from a map information storing medium such as a CD-ROM or the like, stores the extracted map information into a memory such as an IC card or the like, loads only the memory into the mobile navigation apparatus at the time of starting the movement and displays the desired map information by reading this map information from the memory depending on the movement.
However, the mobile navigation apparatus of the related art has been requested, when the amount of map information to be extracted is larger than the capacity of the memory on the occasion of extracting the map information from a map information storing medium, to reduce the amount of the map information to less than the capacity of the memory by deleting a part of the area to be extracted by a user or selecting a map drawn on the smaller scale. Therefore, such a disadvantage as extracting the map information including the desired information has also been generated. The apparatus of the related art also has a disadvantage that the desired map information cannot be displayed when the target destination is changed during the movement. In addition, even if it has been possible to extract the map information from the map information storing medium during the movement, it is requested to delete the map information already stored when the amount of map information to be extracted newly is larger than the capacity of memory and therefore it has been difficult in some cases to store the record of movement.
The present invention has been proposed considering the background explained above and the object of the present invention is to provide a mobile navigation system which can store the desired map information without any limitation on the capacity of the memory, quickly display the desired map information and store the record of movement.
The mobile navigation system of the present invention includes a present position information generating means for detecting the current position of a mobile means to generate present position information, a map information storing means for storing map information, a map information generating means for reading the map information of the predetermined region from the map information storing means based on the present position information to generate a display map information from the map information obtained and a display means for displaying the display map information and the present position information, a moving distance calculating means for calculating a moving distance of the mobile means based on the present position information and the display map information generating means includes a near region map information reading means for reading out, from the map information storing means, the map information of the near region of the region indicated with the display map information every time the mobile means moves for only the predetermined distance and a far region map information storing means for generating the map information in the far region extending along the moving route in which the mobile means has moved from the near region map information and storing such information as the readout map information.
According to the present invention, since the map information of the near region at the external side of the region indicated with the display map information is read for each movement of the predetermined distance of a mobile means from the map information storing means, the map information of the desired region can be stored and displayed. Since the map information obtained is previously stored for each movement of the predetermined distance of the mobile means, the map information can be displayed quickly.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.